1. Field of the Invention
The present invention relates to a process for producing a polymer polyol and a polyurethane obtained by using the polymer polyol. More particularly, it relates to a process for producing a polymer polyol by polymerizing a monomer having a polymerizable unsaturated group in a specific polyol having a polymerizable unsaturated group and a process for producing a polyurethane obtained by using the polymer polyol.
2. Description of the Prior Art
A compound obtained by polymerizing a monomer having a polymerizable unsaturated group in a polyol such as a polyether polyol or a polyester polyol or a mixture thereof is referred to as a polymer polyol. A polymer polyol is used as a starting material for polyurethane foams and polyurethane elastomers. The polymer polyols are classified into two groups. One kind of polymer polyols are obtained by polymerizing a monomer in a polyol having substantially no polymerizable unsaturated group. The polymer polyols in this group are disclosed in U.S. Pat. No. 3,383,351, No. 3,523,093 and British Pat. No. 1,040,452.
The other kind of polymer polyols are obtained by polymerizing a monomer in polyol having a polymerizable unsaturated group. In view of dispersion stability, the latter polymer polyols are considered to be superior, however, in view of easy production and economical consideration, the latter polymer polyols have not been satisfactory.
The present invention relates to the latter polymer polyols.
The polymer polyols obtained by polymerizing a monomer having a polymerizable unsaturated group (referring to as monomer) in a polyol having a polymerizable unsaturated group (referring to as unsaturated polyol) are disclosed in U.S. Pat. No. 3,652,639, No. 3,823,201, No. 3,966,521 and No. 4,032,485.
In these prior arts, the unsaturated polyols are produced by reacting a saturated polyol with an unsaturated polycarboxylic acid such as maleic anhydride, and then, reacting an alkylene oxide; or by reacting an unsaturated epoxide such as allyl glycidyl ether with a saturated polyol. However, when the unsaturated acid is used, the unreacted carboxylic acid group is usually remains or the ester of the unsaturated polyol is easily decomposed in the production of a polymer polyol, to form carboxylic acid group, whereby polymer polyols having high acid value is disadvantageously obtained. The use of the polymer polyol having high acid value in a the production of a polyurethane causes trouble in the reaction for urethane bond, whereby a desired polyurethane can not be obtained. From the technological and economical viewpoints, the known unsaturated polyols are not satisfactory for the production of polyurethanes.